1. Field of the Invention
The present invention is directed toward an electrical connecting device, and more particularly to such connectors that positively engage the plug of an electrical appliance to an extension cord, the plug and receptacle ends of adjacent extension cords, or the plug of an electrical cord to a power outlet, preventing disconnection during tensile stresses and allowing for disconnection only through the manual manipulation of an orientational bias that exists between the plug and receptacle or outlet.
2. Prior Art Statement
Since the advent of electrical appliances and tools, man has had the same recurring problem. The existing plug on the electrical appliance does not reach an electric outlet. This problem was quickly remedied by the invention of the extension cord. However, electrical devices, especially electrical tools, are often moved when operated. This movement stresses the connection between the electrical device and the extension cord, resulting in a premature disconnection. Similarly, when one extension cord does not add the needed length, a series of extension cords are needed to connect an electrical appliance to an outlet. Most people prefer short extension cords to long because the future need for extension cords cannot be foreseen, and since short extension cords can be interconnected to create a long extension cord, shorter extension cords give more versatility and fit more applications than does a long cord. The problem with short extension cords that are combined to create a long cord, is that the points of interconnection between the short cords often become disconnected when the extension cords are pulled. Also, the interconnection points between short cords often bind on objects as the extension cord is moved, the binding causing tensile stress which ultimately causes the disconnection of the shorter cords.
The tendency of interconnected extension cords to bind and disconnect is a well known problem, and over the years many different inventions have been developed to prevent such an occurrence. The prior art which exemplifies the varying types of inventions is as follows:
U.S. Pat. No. 2,291,793 to Chandler shows a receptacle/plug connecting device that uses a hook to secure the plug and receptacle together. The hook prevents the plug and receptacle from pulling apart but the hook can easily become undone as the plug and receptacle are rotated and otherwise manipulated during use:
U.S. Pat. No. 4,907,984 to Keller shows a receptacle and plug that are held together by a strap and buckle, the strap being twisted around the wires of each side. The attachment, removal and use of this invention requires considerable amount of time and effort;
U.S. Pat. No. 3,316,523 to Trangmar shows a plug and receptacle held together by the bias of a leaf spring. The spring biased connection can be defeated if the leaf spring binds against an object during use, or if the spring connection is subject to varying impacts. In such a situation, the plug and receptacle may disengage and the spring bias holding them together may come free and be lost.
U.S. Pat. No. 1,835,251 to Wetstein shows a plug and receptacle held together by clamps. The biasing of the clamps can be easily defeated if the clamp tabs bind or hit upon an object during use.
U.S. Pat. No. 4,917,625 to Haile shows an independent middle piece that connects the plug and receptacle. However, since extension cords are only used periodically and the Haile invention is a small independent piece, it is likely that the Haile invention would be lost, eliminating the binding characteristics of the two extension cords. Also, in large construction sites, where many extension cords are used, there is no way to assure that the Haile invention will be removed and reengaged properly each time the extension cords are used.
U.S. Pat. No. 4,643,505 to House et al, shows a device that envelops the receptacle and plug ends of two extension cords. The receptacle and plug are anchored in place by obstructions that descend from the enveloping encasement. The House patent also exemplifies the first type of engagement device that has a streamlined shape to diminish the binding characteristics of joined cords;
U.S. Pat. No. 3,192,499 to West shows a receptacle and plug wherein one has a flexible finger that engages a relief within the wall of the other. The flexible finger not only ensured a positive engagement but orients the plug and receptacle for proper connection. The flexible finger is attached to the side periphery of the male plug, which is entirely enveloped by the female receptacle. The flexible finger also has a tab extending from it that does not become enveloped by the receptacle. The tab is depressed to deform the flexible finger when the plug and receptacle are to be disconnected.
Thus, although prior art does teach the use of devices that positively engage the plug and receptacle ends of electrical devices and extension cords or adjacent extension cords, prior art does not teach nor suggest an electrical plug engagement device that is streamlined to prevent binding, formed to stay engaged regardless of movement during use, and unistructurally manufactured as part of the plug and receptacle. As such, no prior art anticipates the novel device developed herein.
Similar to the problem of extension cords becoming disconnected is the problem of electrical cords disconnecting from wall sockets. The same technology that is used to interconnect adjacent electrical cords can be designed into the cover of wall sockets and into the plug ends of electrical appliances and power tools. Such a design prevents a plug from becoming desconnected when such an electrical device is moved and the cord is stressed. Similarly, since prior art neither teaches nor suggests the present invention in use to connect electrical devices to extension cords, adjacent electrical extension cords, prior art neither teaches nor suggests the use of the present invention to connect electrical cords to wall receptacles.